This is an exercise in texturing, using the GIMP alongside XSI. The gun is the first person mesh of the ZB-30, made for Carpathian Crosses, a mod for Red Orchestra, possibly soon to be released via Steam.
The model was provided without UVs. I created the UVs, colour map and specular map.
For the colour map I began with a dirtmap layer baked in using ambient occlusion as the shader. A sphere with a basic brown up to blue gradient was used as part of a global illumination pass, layered on top of everything.
A layer of wood was used as reference for the butt and other areas. The metal had a rippled water texture which seemed appropriately random. The rest of the detailing, dirt, grime, wear and tear was hand painted over the top.
The specular was derived from the colour map, removing details that were unnecessary, and enhancing those that were.

Colour map: http://www.ajcgi.co.uk/xs/zb30.jpg
Specular map: http://www.ajcgi.co.uk/xs/zb30spec_1024.jpg